What is the significance of the search for extraterrestrial intelligence in the golden age of astronomy? When will humanity leave its home planet?
In one of the "Cosmicomic Stories" by Italian writer Italo Calvino, entitled "Light Years," the narrator observes a galaxy through a telescope. It's a hundred million light-years away, and she says, "I've seen everything." Terrified, he grabs his diary and finds out that on this very day 200 million years ago he did something that he is ashamed to admit. At first he wants to answer: "I'll explain everything!" Then: "I would have looked at you in my place!" But he stops at the following: "So what?" The narrator gets involved in a long conversation with a distant interlocutor, gradually other, more distant objects are drawn into him, and hundreds of millions of years are spent on each remark.
Well, where the hell are they ?! (Large Magellanic Cloud. Image of the European Southern Observatory.)
Calvino worked in the 1960s - shortly after the discovery of quasars, when we were just beginning to comprehend the nature of the universe and all this was new. But the thought of living in space was far from new. Back in the 6th century BC. e. the ancient Greek philosopher Anaximander taught about the incessant creation and destruction of countless worlds. A century later, Democritus said that the endless movement of atoms inevitably leads to the appearance of a myriad of worlds and living beings in the Universe. In the twelfth century, interpreting the words of the Koran that Allah is the Lord of the worlds, Fakhr ad-din Ar-Razi preached the existence of thousands of thousands of worlds.
In the 17th century, Johannes Kepler, Christian Huygens and other European scientists, inspired by the invention of the telescope, began to predict that one day this device would allow viewing other worlds in every detail. “Perhaps the eye will receive one more help, and with its help we will be able to see living things on the Moon and on other planets,” wrote one of the founders of physics, Robert Hooke in 1665.
Since then, 350 years have passed, and the possibilities of astronomy have reached such heights that Hook and his contemporaries never dreamed of. We see stars forming in clouds of dust and gas. In an area of the sky the size of a grain of sand (if you remove it from the eye at arm's length), the Hubble Space Telescope saw ten thousand galaxies, each of which has billions of stars. We discovered a galaxy that is 13.3 billion light years away (less than 500 million years after the Big Bang).
While it is impossible to see it, we can detect the rotation of the black hole and how relativistic effects warp spacetime near the event horizon. Every decade brings new and startling discoveries, and sometimes they happen every year. And theorists convince us that everything is just beginning. It is believed that more than 95% of energy and matter are inaccessible to our observation. Perhaps our universe is just one of many, and each of them is like a soap bubble inside the Multiverse.
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Places where life can exist appeared before our eyes. The study of planets in the orbits of other stars has entered its prime. More than 900 exoplanets have been discovered and a thousand candidates for this rank, and new ones appear almost every week. Statistical extrapolations indicate that there are 20 billion terrestrial planets in our Galaxy alone. The understanding of these bodies is growing by leaps and bounds. For example, clouds were recently discovered on a planet that is a thousand light years away. Astrobiology constantly revises ideas about the conditions in which life can arise and develop, pushing the boundaries of the possible.
And yet in one respect we are still on a par with Democritus and Hooke. No trace of alien life has been found. Strange, isn't it? Look how long the Universe has existed, how many stars there are in it: aliens must be visible and invisible. In 1950, Enrico Fermi exclaimed: "Where the hell are they ?!"
New York journalist Lee Billings has written a good book about people who have tried and are still trying to answer Fermi's question. His recently released work is called Five Billion Years of Solitude.
First of all, this is a wonderful guide for anyone who knows nothing about the scientific foundations of finding other planets. How, for example, can one see a planet against the background of a distant star, if the star obscures it, like a nuclear explosion - a match?
For those who are well versed in such matters, it will be interesting to read about people who have devoted their lives to exoplanetology from Francis Drake (the initiator of the search for an extraterrestrial civilization and the author of the equation of his name, in which the hypothetical duration of the existence of a civilization is a key factor in assessing the chances that we meet her) to the gushing ideas of Gregory Laughlin and Sarah Seeger, who can literally be called the beacons of a new generation of astronomy.
But perhaps the most interesting part of the book is the one in which Mr. Billings tries to answer the question of how best to protect life on our planet.
Many scientists seriously doubt that we are not alone. Why, then, are all this expensive research needed? The issue is especially relevant now and especially in the United States, which, due to wasteful wars, increased inequality and uncontrolled development of the financial sector, have become hostages of anti-democratic and anti-scientific forces.
There are at least three answers. First, it's too early to lower the curtain. Life can be detected by a certain imbalance of chemicals in the atmosphere of a distant planet. This alone will be an exciting discovery - one of the most important in our history.
Secondly, it doesn't matter what the final conclusion will be - that there is no more life in the Universe, that it is extremely rare, or that it is full. In any case, we will learn to better understand what life is, and this will primarily benefit here on Earth. It is already obvious that human activity is a factor comparable in its impact on the biogeochemical system with the causes of mass extinctions. When it finally comes to us what we are actually doing with our own home, then, perhaps, humanity will take the first step towards true unity with Gaia.
Thirdly, sooner or later the Sun will begin to bake more strongly, and our distant descendants will be able to survive only by moving to another planet. Mr. Billings is confident that it makes sense to start thinking about it today. People speaking on this topic are considered alarmists, since the apocalypse is still very far away: it is not known whether humanity will live to see it, and then - what does it matter to us for these descendants, let them get out themselves! However, the author recalls that it was the fate of mankind that worried and inspired Konstantin Tsiolkovsky when, at the end of the 19th century, he began to dream of missiles, sitting in the Russian wilderness. These are the thoughts that actually gave birth to the space age!
This spring, a team of authors published Starship Century: Toward the Grandest Horizon, in which a number of prominent scientists discussed the reality of an interstellar flight by 2100. According to experts, this is not as impossible as it might seem.
In one of his interviews, Mr. Billings prophesied that our era will be considered “axial” (“axial time” is the term that Karl Jaspers used to designate the era of the birth of philosophy against the background of myth) in the history of intelligent life, and not only on Earth, but also in the entire solar system at least. In his opinion, the chances are high that we will not meet the hopes of future generations, although we have everything in order to spread life and intelligence beyond the Earth. Most likely, human history will end the same way it began - with dirty swarms on a lonely planet lost in space.
But one of the pioneers of quantum computing, David Deutsch, in The Beginning of Eternity, says that for all our maddening scientific advances, the realm of the unknown remains the same as it has always been - infinite. We don't know what the future holds, so let's choose optimism anyway. (And here it is appropriate to recall the statement of a six-year-old boy named Calvin - the hero of the comics of Bill Watterson: “Sometimes it seems to me that the most solid proof of the existence of intelligent life in the universe is that it is not trying to establish contact with us.”)
Probably, first we all need to calm down. In the story "The Universe is Like a Mirror" from the collection "Palomar", which was published after the death of Italo Calvino, Mr. Palomar meditates on space in the hope that this will make him wise and calm. Waking up from cosmic dreams, he discovers that nothing has changed: his life still consists of vanity, doubts, mistakes and melancholy …